Signal transmitting delay time is one of the important AC characteristics of CMOS integrated circuits. Integrating test structures into test chips, taping out and testing the test chips is a common method to test signal transmitting delays. As a result of the characteristics of the ring oscillator's structure, circuit signal transmitting time can be obtained by testing the oscillation frequency of the ring oscillator. Therefore, with the ever increasing integration level, ring oscillator test chips can be used to evaluate the characteristics of integrated circuit effectively. A large amount of test data about manufacture process and yield improvement can be achieved via large amount of tests of the test chips. As such, some valid solutions to improve the product yield and shorten the yield maturity period based on the test data can be realized. Designing test chip highly efficiently through computer-assisted methods has become an important research direction in the area of test chip designs.